A portable function to create a bmp file from raw bytes? [closed]

Question

I have an array of raw bytes and I want to make a bmp file from those bytes. That is, I have to fill bitmap header structre and other things, then write down the bytes so I have a bmp file in the proper format.

As I need this for some quick check only, I wonder if there is a portable method to do this - take raw bytes and save them as a bmp file. Any Windows version won't do as I'm writing that on Unix.

Alternatively, I can save those bytes as any other image format - I only need to have a quick look at the resulting picture.

Answer 1

This is the code I use for .bmp Greyscale images

To save as color bitmap, just make sure about not using the palette (for 24bits)

void SaveBitmapToFile( BYTE* pBitmapBits, LONG lWidth, LONG lHeight,WORD wBitsPerPixel, LPCTSTR lpszFileName )
{
    RGBQUAD palette[256];
    for(int i = 0; i < 256; ++i)
    {
        palette[i].rgbBlue = (byte)i;
        palette[i].rgbGreen = (byte)i;
        palette[i].rgbRed = (byte)i;
    }

    BITMAPINFOHEADER bmpInfoHeader = {0};
    // Set the size
    bmpInfoHeader.biSize = sizeof(BITMAPINFOHEADER);
    // Bit count
    bmpInfoHeader.biBitCount = wBitsPerPixel;
    // Use all colors
    bmpInfoHeader.biClrImportant = 0;
    // Use as many colors according to bits per pixel
    bmpInfoHeader.biClrUsed = 0;
    // Store as un Compressed
    bmpInfoHeader.biCompression = BI_RGB;
    // Set the height in pixels
    bmpInfoHeader.biHeight = lHeight;
    // Width of the Image in pixels
    bmpInfoHeader.biWidth = lWidth;
    // Default number of planes
    bmpInfoHeader.biPlanes = 1;
    // Calculate the image size in bytes
    bmpInfoHeader.biSizeImage = lWidth* lHeight * (wBitsPerPixel/8);

    BITMAPFILEHEADER bfh = {0};
    // This value should be values of BM letters i.e 0x4D42
    // 0x4D = M 0×42 = B storing in reverse order to match with endian

    bfh.bfType = 'B'+('M' << 8);
    // <<8 used to shift ‘M’ to end

    // Offset to the RGBQUAD
    bfh.bfOffBits = sizeof(BITMAPINFOHEADER) + sizeof(BITMAPFILEHEADER) + sizeof(RGBQUAD) * 256;
    // Total size of image including size of headers
    bfh.bfSize = bfh.bfOffBits + bmpInfoHeader.biSizeImage;
    // Create the file in disk to write
    HANDLE hFile = CreateFile( lpszFileName,GENERIC_WRITE, 0,NULL,
        CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL,NULL);

    if( !hFile ) // return if error opening file
    {
        return;
    }

    DWORD dwWritten = 0;
    // Write the File header
    WriteFile( hFile, &bfh, sizeof(bfh), &dwWritten , NULL );
    // Write the bitmap info header
    WriteFile( hFile, &bmpInfoHeader, sizeof(bmpInfoHeader), &dwWritten, NULL );
    // Write the palette
    WriteFile( hFile, &palette[0], sizeof(RGBQUAD) * 256, &dwWritten, NULL );
    // Write the RGB Data
    if(lWidth%4 == 0)
    {
        WriteFile( hFile, pBitmapBits, bmpInfoHeader.biSizeImage, &dwWritten, NULL );
    }
    else
    {
        char* empty = new char[ 4 - lWidth % 4];
        for(int i = 0; i < lHeight; ++i)
        {
            WriteFile( hFile, &pBitmapBits[i * lWidth], lWidth, &dwWritten, NULL );
            WriteFile( hFile, empty,  4 - lWidth % 4, &dwWritten, NULL );
        }
    }
    // Close the file handle
    CloseHandle( hFile );
}